What is CDN?

CDN stands for Content Delivery Network. It is a group of computers which contain the same copy of data and are placed at various locations in a physical network which allows faster access to that data from any location within the network.

Why do we need CDN?

That is a fair question to ask when one thinks in terms of a small number of computers accessing the internet content. However when we think of today’s scale of consumption, we can easily see why the current 10 G-bit network backbone can fall short. Imagine 1 million users of YouTube streaming HD video and you can easily see that the current infrastructure cannot scale with only one location for media content. CDNs bring a copy of the content to the edge servers so that distance between the content and the consumer is reduced improving performance.

What is Windows Azure Content Delivery Network?

Windows Azure Content Delivery Network is Microsoft’s CDN service available as part of Windows Azure. Currently, Windows Azure CDN caches content in US, Europe, Asia and South America. A complete list of all current CDN nodes is available at http://msdn.microsoft.com/en-us/library/gg680302.aspx .

Benefits of using Windows Azure CDN

Allows better performance

User experience is better since consumer does not have to wait for content, esp. multimedia.

How do I get Windows Azure CDN?

To start with, go to http://windows.azure.com and select the “Hosted Services, Storage Accounts and CDN” in the left navigation bar.

Next, select CDN from the available nodes on the left as shown in the picture below.

Click “New Endpoint”.

Click OK on the dialog which is shown (Make sure “Enable CDN” is selected).

After you click OK, you will get a confirmation dialog saying that the “Enable CDN” will take 60 seconds to propagate worldwide.

If you accidentally created an endpoint, you can delete it from button called “Delete endpoint”. You need to select the endpoint you want to delete before the button will be enabled.

After the endpoint is successfully created, you can get the CDN URL for the storage account via the properties pane on the right hand side.

Check out the property “Default HTTP endpoint” which is Windows Azure CDN URL of the Windows Azure Blob service.

For example, in my case, my Windows Azure Blob service had the URL vipulstorageservice.blob.core.windows.net

When I created the endpoint, it got a CDN URL - az55457.vo.msecnd.net

Now, I can use this URL (az55457.vo.msecnd.net) anywhere in my application/website and the content fetching will be done by the CDN service and always provide fast access to my content.

Billing for Windows Azure CDN

Windows Azure enthusiasts should note that the CDN service is an add-on to the Windows Azure service and is billed separately. At the time of writing this article, it costs $0.15 per GB of data transfers between European and North America locations. You can always find up-to-date billing information at http://www.microsoft.com/windowsazure/pricing/#cdn

Summary

In this article, we learned about Windows Azure CDN service. I hope you have found this information useful.

About the author

Vipul Patel is a Software Engineer currently working at Microsoft Corporation. He is currently working in the Microsoft Lync team and has worked in the .NET team earlier in the Base Class libraries and the Debugging and Profiling team. He can be reached at vipul_d_patel@hotmail.com